A three-tiered plunger pump is conventionally known as a pressurizer (such as a pump) which applies high pressure to a fluid (see Japanese Patent Provisional Publication No. 2001-271762). A substance included in a raw material fluid is atomized by charge-pressurizing the raw material fluid and then discharging it into a generator (or a nanomizer) by means of the plunger pump.
The plunger pump has three plungers each connected through a connecting-rod to a crankshaft which is rotatably supported to a crankcase. The plunger pump applies pressure on the raw material fluid inside a pressure chamber by reciprocally moving each plunger with rotation of the crankshaft. More specifically, when each plunger disposed on one end of the pressure chamber reciprocally moves, the raw material fluid is charged from a charge vessel into the pressure chamber through a check valve for charge which is disposed on a lower portion of the other end of the pressure chamber, or the pressured raw material fluid is discharged from the pressure chamber into the generator through a check valve for discharge which is disposed on a upper portion of the other end of the pressure chamber. Under this mechanism, the substance included in the raw material fluid is atomized to a desired particle size according to a nozzle character mounted inside the generator because high pressure (about 150 M Pa) is applied to the raw material fluid.
In a case where the raw material is changed, flushing out members of the plunger pump which contact with the raw material fluid prevents contamination, and thereby a substance included in a post-raw material fluid is not mixed with a substance included in a prior-raw material fluid. However, it takes a lot of work to flush out the members because the conventional pressurizer has many members.
Further, the check valve for charge has some problems in dependence upon a raw material fluid's character. The check valve has a valve seat, a valve body and a coil spring. The valve seat is disposed between the charge vessel and the pressure chamber. The valve body is formed of a metal sphere. One end and the other end of the coil spring are connected to the valve body and an interior of the check valve, respectively. The coil spring presses the valve body against the valve seat and then prevents the raw material fluid from flowing back from the pressure chamber into the charge vessel at the time of a pressure operation of the plunger pump.
In the check valve for charge taking such a configuration, the following three problems arise in dependence upon the raw material fluid' character. Firstly, if the raw material fluid's viscosity is high, the raw material fluid blocks the check valve. Therefore, it is necessary to mount a pressure feed pump into the charge vessel and forcibly push the raw material fluid out of the check valve. Secondly, if a particle size of a substance included in the raw material fluid is large, the substance always creates a space between the valve body and the valve seat. Therefore, the raw material fluid flows back at the time of a pressure operation of the plunger pump. Thirdly, if there is a different specific gravity among substances included in the raw material fluid, a substance having a high specific gravity is deposited at the bottom of the charge vessel. Therefore, it is necessary to equalize distribution of the substances inside the charge vessel by means of an agitator.
The present invention is proposed in view of actual conditions. An object of the present invention is to provide an atomizing apparatus incorporating a pump therein for allowing a raw material fluid to flow back from a pressure chamber into a charge vessel in the first half of a discharge stroke and preventing the raw material fluid from flowing back from the pressure chamber into the charge vessel in the last half of the discharge stroke, and giving an easy flushing work.